TX-DS797 Sound cuts out when swithching to Dolby Digital

I have a TX-DS797 that I purchased new. 21Y0026553 It has had a warranty repair once before for amplifier issues causing the sound to cut out completely.
I use a Dish Network VIP 722 receiver to send sound through an optical cable to the receiver. On certain commercials I will need to tap the receiver for the sound to come back on. I have tried different optical cables and still the problem. I have switched the inputs from optical 1,2, and 3 and still the problem. It seems when the source is non Dolby Digital the sound cuts and will not switch back on.
I notice that the "red rectangle" around the Dolby Digital on the front panel will not be illuminated until I tap on the receiver. When the "red rectangle" illuminates the sound comes back on.
I've tried other sources such as DVD players and have the same problem when I switch the sound from non Dolby to Dolby Digital.

I don't have to tap the receiver very hard for the sound to come back on or sometimes I just need to touch it.

Any advice would be much appreciated.
Thanks

In regards to your issue- it would possibly be more effective to contact our Product Support Dept for further assistance with this specific issue via our phone number and hours of operation below. We would like to speak with you and work to troubleshoot and resolve your issue, with you having access to your unit, as prompt as possible. Please contact our Product Support Dept for further assistance with this specific issue via our phone number and hours of operation (Monday- Sunday 24 hours a day: (800) 229-1687; option #3 PRODUCT SUPPORT). We would like to speak with you and work to troubleshoot and resolve your issue as prompt as possible.

Thank You;

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